The present application claims priority to Japanese Application No. P11-292885 filed Oct. 14, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, more specifically to a method of manufacturing a semiconductor device, which is capable of forming a desired electrode pattern by a simple process at low cost. Particularly, the present invention relates to a method of manufacturing a solar cell capable of decreasing the ineffective electrode area, which does not contribute to electric power generation, by a simple process at low cost, improving conversion efficiency.
2. Description of the Related Art
In a semiconductor device, generally, a first semiconductor layer is formed on the surface of a silicon substrate, a second semiconductor layer is formed on the first semiconductor layer, and then an electrode pattern is formed.
In this case, a photoresist mask or the like is conventionally used for forming the electrode pattern.
Although the electrode pattern can be formed in a desired pattern by this method, the use of the photoresist mask requires chemical treatments such as etching and mask removal, thereby causing the problem of complicating the process to increase the required time and cost.
Particularly, as disclosed in Japanese Unexamined Patent Publication No. 8-21345, for example, a thin film single crystal silicon solar cell is formed on a polycrystalline silicon layer formed on the surface of a single crystal silicon substrate, and the formed thin film single crystal silicon solar cell is separated from the single crystal silicon substrate, and transferred onto a plastic substrate to produce a thin film single crystal silicon solar cell. In the thus-produced thin film single crystal silicon solar cell, an electrode must be formed before the thin film single crystal silicon solar cell is separated from the single crystal substrate because of the low heat resistance of the plastic substrate. Therefore, anode and cathode must be inevitably formed on the surface of the solar cell on which light is incident, thereby causing the problem increasing the ineffective electrode area not contributing to power generation. In such a case, a photoresist mask is conventionally used to attempt to decrease the ineffective electrode area. However, the need for chemical treatments such as etching and mask removal complicates the process to increase the required time and cost.
Accordingly, the present invention provides a method of producing a semiconductor device which is capable of forming a desired electrode pattern by a simple process at low cost.
Another object of the present invention is to provide a method of manufacturing a solar cell, which is capable of decreasing the ineffective electrode area not contributing to power generation, by a simple process at low cost, thereby improving conversion efficiency.
The objects of the present invention can be achieved by a method of manufacturing an electronic device, comprising forming a first semiconductor layer on a substrate, forming a second semiconductor layer on the first semiconductor layer, and removing the second semiconductor layer in a predetermined pattern by using laser abrasion to expose the first semiconductor layer, to form an electrode pattern.
In the present invention, the semiconductor layer is removed in the predetermined pattern by laser abrasion, which permits fine patterning, to expose the first semiconductor layer, thereby permitting the manufacture of a semiconductor device having the desired electrode pattern by a simple process at low cost without using a photoresist mask or the like.
In a preferred embodiment of the present invention, the substrate is a silicon substrate.
In another preferred embodiment of the present invention, the silicon substrate is a single crystal silicon substrate.
In still another preferred embodiment of the present invention, the single crystal silicon substrate is a thin film single crystal silicon substrate.
In a further preferred embodiment of the present invention, the first semiconductor layer is formed on the substrate with a porous layer provided therebetween to produce a semiconductor device.
In a still further preferred embodiment of the present invention, the substrate is separated in the porous layer portion so that the first and second semiconductor layers are respectively supported by separate support substrates to enable reuse of the substrate.
In a further preferred embodiment of the present invention, the porous layer is a porous silicon layer.
In a further preferred embodiment of the present invention, the first semiconductor layer is a p-type semiconductor layer, and the second semiconductor layer is a n-type semiconductor layer.
In a further preferred embodiment of the present invention, the first semiconductor layer and the second semiconductor layer are formed by epitaxial growth to manufacture a semiconductor device.
In a further preferred embodiment of the present invention, the first semiconductor layer is partially removed according to the formed electrode pattern to form an electrode, manufacturing a semiconductor device.
In a further preferred embodiment of the present invention, after the electrode is formed, the substrate is bonded to a transparent substrate, and then separated in the porous layer portion, and a support substrate is bonded to the back of the first semiconductor layer to manufacture a semiconductor device.
In a further preferred embodiment of the present invention, the transparent substrate comprises a plastic film.
In a further preferred embodiment of the present invention, a semiconductor device can be made lightweight and flexible, and can be manufactured at low cost.
In a further preferred embodiment of the present invention, the support substrate comprises a plastic film.
In a further preferred embodiment of the present invention, the strength of the porous layer is decreased by using ultrasonic energy so that the substrate is separated in the porous layer portion to manufacture a semiconductor device.
In a further preferred embodiment of the present invention, before the support substrate is bonded to the back of the first semiconductor layer, the porous layer remaining on the surface of the first semiconductor layer is removed to manufacture of a semiconductor device.
In a further preferred embodiment of the present invention, after the electrode is formed, the substrate is bonded to a support substrate, and then separated in the porous layer portion, and a transparent substrate is bonded to the back of the first semiconductor layer after a protecting layer of silicon oxide is formed at low temperature on the back of the first semiconductor layer,
In a further preferred embodiment of the present invention, at least one porous film is formed to pass through the first and second semiconductor layers between the formation of the first semiconductor layer and the second semiconductor layer and the formation of the electrode pattern, and the at least one porous layer is thermally oxidized to form at least one insulating separation film so that adjacent devices comprising the adjacent first and second semiconductor layer are insulated and separated from each other to manufacture a semiconductor device.
In a further preferred embodiment of the present invention, not less than two porous films are formed.
In a further preferred embodiment of the present invention, the porous films comprise porous silicon.
In a further preferred embodiment of the present invention, the first and second semiconductor layers constitute a light generating device.
In a further preferred embodiment of the present invention, a solar cell can be manufactured at low cost by a simple process, in which the ineffective electrode area, which does not contribute to power generation, is decreased to improve conversion efficiency. Namely, the solar cell is produced by forming an electrode on a substrate, bonding the substrate to a transparent substrate, separating the substrate in the porous layer portion, and bonding a support substrate to the back of the first semiconductor layer. In this case, the first semiconductor layer is removed in the predetermined pattern by laser abrasion, which permits fine patterning, to expose the second semiconductor layer, thereby decreasing the ineffective electrode area, and manufacturing a single cell-type solar cell having the desired electrode pattern. A solar cell can also be manufactured by forming an electrode on a substrate, bonding the substrate to a support substrate, separating the substrate in the porous layer portion, forming a protecting layer of silicon oxide on the back of the first semiconductor layer at low temperature, and bonding a transparent substrate to the back of the first semiconductor layer. In this case, a back contact-type solar cell can be manufactured, in which light is incident on the back, and the ineffective electrode area can be significantly decreased to improve conversion efficiency. A solar cell may be manufactured by forming first and second semiconductor layers, forming at least one porous film to pass through the first and second semiconductor layers, and thermally oxidizing the at least one porous film to form at least one insulating separation film so that adjacent devices comprising the adjacent first and second semiconductor layers are insulated and separated from each other before an electrode pattern is formed. In this case, the at least one porous film formed to pass through the first and second semiconductor layers is thermally oxidized to form the insulating separation film, thereby insulating and separating the adjacent devices. Therefore, a back contact-type integrated solar cell can be manufactured with a high working efficiency without separation of the first and second semiconductor layers from the substrate in manufacturing.